Documentation sections

Charge Pump Voltage Multiplier Calculator

POSThttps://rftools.io/api/py/v1/calculate

Slug charge-pump-voltage. Calculate Dickson charge pump output voltage, loaded voltage, output ripple, and efficiency for switched-capacitor voltage multiplier circuits

Inputs

Send every one of these in inputs, in the units shown. Most are required: a call without one is refused (400) and costs nothing; one the calculator can do without takes the default shown. An input outside its range is still computed and flagged in the provenance.

Inputs of charge-pump-voltage
Name	Unit	Range	Default	Description
inputVoltagenumber	V	at least 0.1	3.3	Input Voltage
stagesnumber	none	1 … 8	2	Number of Stages
pumpCurrentnumber	mA	at least 0.001	10	Load current drawn from charge pump output
frequencynumber	kHz	at least 0.1	100	Switching Frequency
capacitancenumber	μF	at least 0.001	1	Capacitance of each pump capacitor stage
inputVoltageMinnumber	V	at least 0	0	The lowest input the pump must work from; 0 for the nominal. The lowest output is taken there.
inputVoltageMaxnumber	V	at least 0	0	The highest input the pump must work from; 0 for the nominal. The parts' voltage ratings are taken there.
pumpCurrentMinnumber	mA	at least 0	0	The lightest load; 0 for the nominal. The highest output is taken there.
pumpCurrentMaxnumber	mA	at least 0	0	The heaviest load; 0 for the nominal. The ripple and the switch current are taken there.
switchResistancenumber	Ω	0 … 100000	1	Each of the 3N + 1 switches (N + 1 transfer switches and a pair driving each pump capacitor) carries the output charge once a period and adds 2·R_on to the output resistance.
esrnumber	mΩ	0 … 100000	10	Each pump capacitor adds 4·ESR to the output resistance, the output capacitor 1·ESR.

Outputs

Returned in values, by key. A value that is unbounded or undefined is null.

Outputs of charge-pump-voltage
Field	Unit	Description
openCircuitVoltage	V	Open Circuit Voltage
loadedVoltageheadline	V	Loaded Output Voltage
outputRipple	mV	Output Ripple
efficiency	%	Efficiency
loadedVoltageMin	V	At the minimum input and the maximum load
loadedVoltageMax	V	At the maximum input and the minimum load
openCircuitVoltageMax	V	At the maximum input: what the output capacitor and the load must stand with no load
openCircuitVoltageVin	V	Input at the Highest Open Circuit Voltage
outputRippleWorst	mV	Output Ripple, Worst Case
outputRippleWorstI	mA	Load at the Worst Ripple
inputCurrentMA	mA	The average input current, (N + 1) times the load
inputCurrentI	mA	Load at the Worst Input Current
pumpCapCount	none	Pump Capacitors
pumpCapVoltageRating	V	The rating sold at or above 1.5 times what the last pump capacitor holds, N·V_in at the maximum input
outputCapVoltageRating	V	The rating sold at or above 1.5 times the open circuit voltage at the maximum input
switchCount	none	N + 1 transfer switches and a pair driving each pump capacitor
switchVoltageRating	V	The rating sold at or above 1.5 times what a switch blocks at the maximum input: 2·V_in between inner stages, V_in in a doubler
switchRmsMA	mA	√2 times the load: twice the load for half of each period, in the fast-switching limit
switchRmsI	mA	Load at the Worst Switch Current
chargeSharingResistance	Ω	N/(f·C), the output resistance today's model uses
outputResistance	Ω	The charge-sharing resistance plus the switches' and the capacitors' ESR, added (an upper bound)
loadedVoltageWithLosses	V	Loaded Output Voltage with Losses
lossChargeSharing	W	Charge-Sharing Loss
lossSwitches	W	Switch Conduction Loss
lossCapEsr	W	Capacitor ESR Loss
lossTotal	W	Total Loss
outputPower	W	Output Power
efficiencyLossModel	%	At the nominal input and load, with the switches' resistance and the capacitors' ESR; with both at 0 it is today's efficiency

Calling it

Calculate: one call, the request and response in full, and its errors.
Batch: this calculator with others, or a sweep, in one request.
Solve for a target: the value of one input that brings an output to a target.

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "X-API-Key: $RFTOOLS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "slug": "charge-pump-voltage",
    "inputs": {
      "inputVoltage": 3.3,
      "stages": 2,
      "pumpCurrent": 10,
      "frequency": 100,
      "capacitance": 1,
      "inputVoltageMin": 0,
      "inputVoltageMax": 0,
      "pumpCurrentMin": 0,
      "pumpCurrentMax": 0,
      "switchResistance": 1,
      "esr": 10
    }
  }'

import rftools

client = rftools.Client()  # reads RFTOOLS_API_KEY, or the key `rftools login` saved

result = client.calculate("charge-pump-voltage", {
    "inputVoltage": 3.3,
    "stages": 2,
    "pumpCurrent": 10,
    "frequency": 100,
    "capacitance": 1,
    "inputVoltageMin": 0,
    "inputVoltageMax": 0,
    "pumpCurrentMin": 0,
    "pumpCurrentMax": 0,
    "switchResistance": 1,
    "esr": 10,
})
print(result.values)
print(result.warnings, result.provenance.formula_ref)

const response = await fetch("https://rftools.io/api/py/v1/calculate", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.RFTOOLS_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "slug": "charge-pump-voltage",
    "inputs": {
      "inputVoltage": 3.3,
      "stages": 2,
      "pumpCurrent": 10,
      "frequency": 100,
      "capacitance": 1,
      "inputVoltageMin": 0,
      "inputVoltageMax": 0,
      "pumpCurrentMin": 0,
      "pumpCurrentMax": 0,
      "switchResistance": 1,
      "esr": 10
    }
  }),
});
console.log(response.status, await response.json());

package main

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	body := []byte(`{
	  "slug": "charge-pump-voltage",
	  "inputs": {
	    "inputVoltage": 3.3,
	    "stages": 2,
	    "pumpCurrent": 10,
	    "frequency": 100,
	    "capacitance": 1,
	    "inputVoltageMin": 0,
	    "inputVoltageMax": 0,
	    "pumpCurrentMin": 0,
	    "pumpCurrentMax": 0,
	    "switchResistance": 1,
	    "esr": 10
	  }
	}`)
	req, err := http.NewRequest("POST", "https://rftools.io/api/py/v1/calculate", bytes.NewReader(body))
	if err != nil {
		panic(err)
	}
	req.Header.Set("X-API-Key", os.Getenv("RFTOOLS_API_KEY"))
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}

application/json

{
  "slug": "charge-pump-voltage",
  "values": {
    "openCircuitVoltage": 9.899999999999999,
    "loadedVoltage": 9.7,
    "outputRipple": 100,
    "efficiency": 97.97979797979798,
    "loadedVoltageMin": 9.7,
    "loadedVoltageMax": 9.7,
    "openCircuitVoltageMax": 9.899999999999999,
    "openCircuitVoltageVin": 3.3,
    "outputRippleWorst": 100,
    "outputRippleWorstI": 10,
    "inputCurrentMA": 30,
    "inputCurrentI": 10,
    "pumpCapCount": 2,
    "pumpCapVoltageRating": 10,
    "outputCapVoltageRating": 16,
    "switchCount": 7,
    "switchVoltageRating": 12,
    "switchRmsMA": 14.142135623730951,
    "switchRmsI": 10,
    "chargeSharingResistance": 20,
    "outputResistance": 34.09,
    "loadedVoltageWithLosses": 9.559099999999999,
    "lossChargeSharing": 0.002,
    "lossSwitches": 0.0014,
    "lossCapEsr": 0.000009,
    "lossTotal": 0.003409,
    "outputPower": 0.095591,
    "efficiencyLossModel": 96.55656565656567
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:charge-pump-voltage",
    "version": "api@3f2c1a9b04de",
    "formulaRef": "Dickson, IEEE JSSC 11(3), 1976; Seeman & Sanders, IEEE TPEL 23(2), 2008",
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "inputVoltage": {
          "min": 0.1,
          "max": null,
          "unit": "V"
        },
        "stages": {
          "min": 1,
          "max": 8,
          "unit": ""
        },
        "pumpCurrent": {
          "min": 0.001,
          "max": null,
          "unit": "mA"
        },
        "frequency": {
          "min": 0.1,
          "max": null,
          "unit": "kHz"
        },
        "capacitance": {
          "min": 0.001,
          "max": null,
          "unit": "μF"
        },
        "inputVoltageMin": {
          "min": 0,
          "max": null,
          "unit": "V"
        },
        "inputVoltageMax": {
          "min": 0,
          "max": null,
          "unit": "V"
        },
        "pumpCurrentMin": {
          "min": 0,
          "max": null,
          "unit": "mA"
        },
        "pumpCurrentMax": {
          "min": 0,
          "max": null,
          "unit": "mA"
        },
        "switchResistance": {
          "min": 0,
          "max": 100000,
          "unit": "Ω"
        },
        "esr": {
          "min": 0,
          "max": 100000,
          "unit": "mΩ"
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "inputVoltage": 3.3,
      "stages": 2,
      "pumpCurrent": 10,
      "frequency": 100,
      "capacitance": 1,
      "inputVoltageMin": 0,
      "inputVoltageMax": 0,
      "pumpCurrentMin": 0,
      "pumpCurrentMax": 0,
      "switchResistance": 1,
      "esr": 10
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "inputVoltage"
      ],
      "msg": "Input should be a valid number, unable to parse string as a number",
      "input": "abc"
    }
  ]
}

An input sent as text. Nothing was counted.

{
  "detail": "More than 120 requests in 60 seconds from this address.",
  "errorKind": "rate_limited",
  "limit": 120,
  "windowSeconds": 60,
  "upgradeUrl": "https://rftools.io/pricing/"
}

Too many requests in a minute, with Retry-After.

Same inputs on the calculator pageCharge Pump Voltage Multiplier Calculator, at these values